Spacing Behavior of Eurasian Three-Toed Woodpeckers (Picoides Tridactylus) During the Breeding Season in Germany

Abstract

Abstract Data on spacing behavior of the Eurasian Three-toed Woodpecker (Picoides tridactylus) are rare, and systematic observations are lacking. I used homing technique (>90%) and triangulation to document range use of 28 radiotagged birds in an alpine mountain forest in southeastern Germany between 1994 and 2000. Common home range of a pair (x ± SE, n = 10) identified by the adaptive kernel method (95% use distribution) during the nesting period averaged 86.4 ± 23.4 ha and varied a great deal between pairs (range 33.9–287.4 ha). Although ranges of females (69.4 ± 15.4 ha, n = 14) appeared larger than those of males (45.7 ± 10.3 ha, n = 10), the difference was not significant. Prior to nesting and during the postnesting period, both sexes used seemingly larger home ranges than during nesting (≤381.7 ha); but again, the difference was not significant. Home ranges of mates (n = 20) during the nesting period overlapped an average of 66.5 ± 5.7% (≤100.0%); female ranges and core areas overlapped male ranges to a significantly greater extent than male ranges overlapped those of females. Nearly all home ranges bordered or overlapped those of their neighbors. Ranges of neighboring male-female combinations (n = 11) overlapped by 17.6 ± 3.9% during the nesting period, with an increasing tendency to overlap toward the end of the breeding season. Because areas used by Eurasian Three-toed Woodpeckers remained stable over the breeding season, I propose consideration of home ranges during nesting as a reliable estimate of species area requirements for use in management plans.